Groups > comp.lang.java.programmer > #39640

Re: InetAddress.isReachable() ?

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From	Arne Vajhøj <arne@vajhoej.dk>
Newsgroups	comp.lang.java.programmer
Subject	Re: InetAddress.isReachable() ?
Date	Fri, 23 Oct 2020 20:30:51 -0400
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On 10/23/2020 7:10 PM, Knute Johnson wrote:
> On 10/23/20 12:14 PM, Arne Vajhøj wrote:
>> On 10/23/2020 12:50 PM, Knute Johnson wrote:
>>> InetAddress.isReachable() only works if I run Java as root.  Any idea 
>>> how to make it work with a regular user?  The docs say "A typical 
>>> implementation will use ICMP ECHO REQUESTs if the privilege can be 
>>> obtained".  I'm assuming that's why it won't work as a regular user.
>>
>> Is it worth it?
> 
> Yes

OK.

>> The method can return false and the service you want to use
>> can be available (firewall blocking ICMP and Echo but not application
>> protocol).
> 
> No firewalls there.
> 
>> The method can return true and the service you want to use
>> can be unavailable (OS running but server application down).
> 
> No service to connect to.  Just want to see if there is a path to the 
> router.
> 
>> I think you would be better of connecting to the service
>> you want to use and handle errors there.
> 
> Again no service to connect to.
> 
> It's an internal network and I'm fielding calls all the time that 'we 
> aren't getting updates to our data'.  If I can ask is the little box 
> green or red I'll know with some certainty the status of their network 
> connection.  I'm 1600 km from the site so I can't just pop over for a 
> look see.  I can't ask them to ping the router, that's a step too far. 
> The network service at the remote sites is interrupted on a fairly 
> regular basis.
> 
> So yes I would really like to figure out how to make this work is it is 
> possible.

I cannot believe there are any ways to get around the privilege issue.

If there were then it would be a bug that would be fixed.

That leaves you with the awful hack of running the external
ping command and read output.

Arne

Thread

InetAddress.isReachable() ? Knute Johnson <knute2020@585ranch.com> - 2020-10-23 11:50 -0500
  Re: InetAddress.isReachable() ? Arne Vajhøj <arne@vajhoej.dk> - 2020-10-23 13:14 -0400
    Re: InetAddress.isReachable() ? Knute Johnson <knute2020@585ranch.com> - 2020-10-23 18:10 -0500
      Re: InetAddress.isReachable() ? Arne Vajhøj <arne@vajhoej.dk> - 2020-10-23 20:30 -0400
        Re: InetAddress.isReachable() ? Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2020-10-23 19:38 -0500
          Re: InetAddress.isReachable() ? Martin Gregorie <martin@mydomain.invalid> - 2020-10-24 11:45 +0000
            Re: InetAddress.isReachable() ? Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2020-10-29 15:23 -0500
              Re: InetAddress.isReachable() ? Martin Gregorie <martin@mydomain.invalid> - 2020-10-29 21:36 +0000
              Re: InetAddress.isReachable() ? Arne Vajhøj <arne@vajhoej.dk> - 2020-10-29 21:47 -0400
                Re: InetAddress.isReachable() ? Knute Johnson <knute2020@585ranch.com> - 2020-11-01 10:30 -0600

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